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Friday, 23 March 2012

Mind games

Think of a two digit number, containing two different odd digits. Write that number down and see the small note at the end of this post.

Professor Chris French gave a talk about Anomalistic Psychology at the Reading Skeptics in the Pub meeting last week.

Chris French - former editor of 'The Skeptic' magazine

Touching on diverse topics including dowsing, psychic abilities, spoon bending, card tricks and paranormal experiences, he gave a whistle-stop tour through the science that explains how our brains are so easily confused. He explained that he spends his life taking a scientific approach to these investigations because so many people have superstitious beliefs. This popularity must suggest that it is an important part of 'being human' and therefore it is worth understanding it properly.

One of the disturbing effects that he described was that of eye-witness testimony. Basically it is now well established that such testimony can not be trusted, and yet every legal system in the world relies on it. We all mis-remember details, and surprisingly it is even found that the reliability is not improved when there are multiple witnesses. It actually becomes worse! Any opportunity that the witnesses might have to discuss what they have seen, they accidentally contaminate each other's memories without realising it.

These results come from the staging of mock crimes. It has been found that at least 40% of people are susceptible to 'suggestions' from others. Errors might even be introduced accidentally by someone who is investigating the crime. If a 'stooge' is introduced too, the proportion of people who unwittingly modify their testimony can rise to 60%.

Moving on from the fascinating talk by Chris, these interesting reports resonate strongly with other research on the same topic. I have heard reports of witnesses being influenced, either accidentally or on purpose, by investigating officers. Just a simple question like 'Did you see a red car at the scene?' could plant the idea of red cars in the memory, even if their initial answer had been to deny noticing the car. The next time the memory is recalled, the red car has a chance of featuring in it.

Some institutions actually train their staff in techniques to minimise the risk of memory contamination though. Banks are aware that accurate reporting of the facts can lead to better investigations, with a greater chance of stolen money being recovered. They know that once people have had chance to confer they tend to converge on a single narrative and forget other essential details.

One way to avoid that is to take contemporaneous notes - which is something that police are trained to do. Something that is written down at the time carries much more weight than something that is remembered later. Hence in the more progressive institutions, staff are trained how to behave after an incident. They are told to sit down on their own and write down everything that they can remember, before talking to anyone else.

Armed with a little knowledge about eye witness testimony, it makes me fear for the justice system. How many people are wrongly convicted because of false memories?

On the other hand it also gives me a lot of hope that it is a good way to explain personal religious revelations without having to resort to a supernatural explanations!

Small note: Relating to the first line of this post, Chris French told us that 33% of people choose 37, and 25% choose 35. I don't know whether you chose one of those numbers, but I did, and I think its scary how predictable we are!

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